https://www.khanacademy.org/science/biology/human-biology/circulatory-pulmonary/v/circulatory-system-and-the-heart 2024-05-06T19:22:43.24334365Z Circulatory system and the heart Hemoglobin, found in red blood cells, absorbs oxygen, increasing the diffusion gradient. This process encourages oxygen to cross the membrane. Hemoglobin is contained within red blood cells to prevent blood from becoming too thick. The blood flows from the heart to the lungs via the pulmonary artery, gets oxygenated, and returns to the heart via the pulmonary vein. The oxygenated blood is then pumped to the rest of the body. Sal Khan video https://cdn.kastatic.org/googleusercontent/QQ3kDKa7ct44EUTcIZwN312V1-RrEgNJruMr8OSIco3MqyTZIfh9-PUfndLKhLpV7f1nQNq58WmnIysS_iLr1Bd7Dw Circulatory system and the heart Hemoglobin, found in red blood cells, absorbs oxygen, increasing the diffusion gradient. This process encourages oxygen to cross the membrane. Hemoglobin is contained within red blood cells to prevent blood from becoming too thick. The blood flows from the heart to the lungs via the pulmonary artery, gets oxygenated, and returns to the heart via the pulmonary vein. The oxygenated blood is then pumped to the rest of the body. https://cdn.kastatic.org/ka-youtube-converted/QhiVnFvshZg.mp4/QhiVnFvshZg.mp4 897 Animals' circulatory system https://www.khanacademy.org/science/health-and-medicine/circulatory-system/blood-vessels/v/arteries-vs-veins-what-s-the-difference 2023-09-10T17:11:17.624018169Z Arteries vs. veins - what's the difference? Explore the roles of arteries and veins in the circulatory system. Uncover common misconceptions about oxygenated and deoxygenated blood, and learn the true distinction: arteries carry blood away from the heart, while veins transport blood towards the heart. Delve into the high-pressure nature of arteries and the low-pressure, high-volume characteristics of veins. Rishi Desai video https://cdn.kastatic.org/googleusercontent/x2Vu8mDkRGVuCk7yG7tz8kKSROmZuOQ0BQtmxuIV3PM8BZLr_r1Aygs2JLAhiuV_8WXT_XPSDdR4eHmqW6_TO5ffIQ Arteries vs. veins - what's the difference? Explore the roles of arteries and veins in the circulatory system. Uncover common misconceptions about oxygenated and deoxygenated blood, and learn the true distinction: arteries carry blood away from the heart, while veins transport blood towards the heart. Delve into the high-pressure nature of arteries and the low-pressure, high-volume characteristics of veins. https://cdn.kastatic.org/ka-youtube-converted/lXkfZYlnwl4.mp4/lXkfZYlnwl4.mp4 464 Animals' circulatory system https://www.khanacademy.org/science/health-and-medicine/circulatory-system/circulatory-system-introduction/a/the-heart-is-a-double-pump 2025-06-30T13:27:22.980068417Z The heart is a double pump article https://www.khanacademy.org/science/hs-bio/x230b3ff252126bb6:from-cells-to-organisms/x230b3ff252126bb6:human-body-systems/a/hs-the-circulatory-system-review 2026-04-26T16:30:39.382257956Z Learn: The circulatory system review Learn about the organs and functions of the circulatory system. article https://www.khanacademy.org/science/bridge-course-class-10th-science/x37589313f9a4c197:untitled-78/x37589313f9a4c197:transportation/e/transport-in-animals 2026-04-30T07:30:36.209464894Z Vessels and Heart Let's solve some questions on Vessels and Heart Vibhor Pandey exercise https://www.khanacademy.org/science/als-k-to-12-science/x46c2fc9f8e023990:2nd-quarter/x46c2fc9f8e023990:the-cardiovascular-system-structure-and-its-vital-functions/e/circulatory-system-questions 2024-11-18T16:44:21.627686931Z Circulatory system questions Circulatory system questions Lucas Philipp exercise https://www.khanacademy.org/science/grade-5-science-pakistan-national-curriculum/x5132c0690d5e9b7d:structure-and-function-human-body-systems/x5132c0690d5e9b7d:human-circulatory-system/e/human-circulatory-system-basic 2026-06-02T08:30:45.964340788Z Human Circulatory System - Basic This exercise will ask basic questions regarding human circulatory system to check understanding of structure and function of organs involved. Asma Rouf exercise https://www.khanacademy.org/science/health-and-medicine/circulatory-system-diseases/x6e556f83:quizzes/e/heart-quiz 2026-04-07T23:55:07.30621384Z Introductory circulatory system quiz Rishi exercise